Application property "server.servlet.session.timeout" is not working in Spring Boot project

I am posting answer because this scenario is new for me. And I haven't got proper solution step by step. According to the suggestion of M. Deinum I created a web.xml file under WEB-INF folder. Project structure is like

src
 |_ main
     |_ java
     |_ resources
     |_ webapp
         |_ WEB-INF
              |_ web.xml

And in web.xml I configured <session-timeout>...</session-timeout>

My web.xml is like

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xmlns="http://java.sun.com/xml/ns/javaee"
         xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
         id="WebApp_ID" version="2.5">


    <session-config>
        <session-timeout>5</session-timeout>
    </session-config>

</web-app>

And now session time of my webapp in server is working according to my configuration. Thanks goes to M. Deinum

You can use Approach 1:

server.servlet.session.timeout=30s
server.servlet.session.cookie.max-age=30s

It is working fine for me

A possible cause for this problem might be using @EnableRedisHttpSession. As explained in this answer:

By using @EnableRedisHttpSession you are telling Spring Boot that you want to take complete control over the configuration of Redis-based HTTP sessions. As a result, its auto-configuration backs off and server.servlet.session.timeout has no effect. If you want to use server.servlet.session.timeout then you should remove @EnableRedisHttpSession. Alternatively, if you want to use @EnableRedisHttpSession then you should use the maxInactiveIntervalInSeconds attribute to configure the session timeout.

Hope this helps someone.